Add proper include guard.
This header gets included by enabling dynamic lookup, and by RegisterModule() of G__Meta.
We need the latter for the many-pcm case.


git-svn-id: https://root.cern.ch/svn/root/trunk@48703 27541ba8-7e3a-0410-8455-c3a389f83636
From Olivier: hide x11 headers from ROOT's headers.


git-svn-id: https://root.cern.ch/svn/root/trunk@48705 27541ba8-7e3a-0410-8455-c3a389f83636
Fix warnings on Fedora 17/18 (const correctness)


git-svn-id: https://root.cern.ch/svn/root/trunk@48706 27541ba8-7e3a-0410-8455-c3a389f83636